PB2527: COMPARING REAL-LIFE VERSUS PREDICTED PARAMETERS WITH OPTIA SPECTRA IN RED BLOOD CELL EXCHANGE IN SICKLE-CELL DISEASE PATIENTS
Authors: Pablo Palomo Rumschisky, Maria Tenorio Núñez, Kyra Velázquez Kennedy, Ana Jiménez Martín, Ana Vallés Carbonero, Alberto González Rodríguez, Blanca De Felipe Noguerales, Lucia Bolea, Francisco Lopez Jimenez, Gemma Moreno-Jiménez
Journal: HemaSphere (2023)

Topic: 26. Sickle cell disease Background: Transfusion therapy is frequent in patients with Sickle-cell disease (SCD). Automated red blood cell exchange (RBCX) can be used to manage acute and chronic complications of SCD. Advantages of RBCX versus simple red blood cell transfusions include less iron and volume overload. It consists of an isovolumetric transfusion that decreases HbS to a predefined level without increasing the hematocrit, which is important to avoid hyperviscosity, that can aggravate the symptoms. Aims: To analyze the correlation between actual and predicted postapheresis hematocrit and HbS in RBCX is SCD patients performed in our center. To establish accuracy of our procedure we also studied efficacy in terms of % HbS reduction. Methods: We present a two years (2021 and 2022) retrospective study of RBCX procedures performed in our center. We used Spectra Optia apheresis system using a “depletion/exchange” protocol. We introduce de following data: fraction of cells remaining (28-30%) considering previous transfusions (HbS target/ preapheresis HbS x 100); the desired postapheresis hematocrit and the mean hematocrit of the red blood cells units (RBCU) according to quality parameters provided by our regional transfusion center. RBCU are fresh (<7 days old), phenotypically matched (Rh, K, Jk, Fy(a) and S antigens) and HbS negative. We use acid citrate dextrose as anticoagulant at 13:1 ratio. Results: We performed RBCX in 10 patients with a median age of 27 years (range 9-55), 9 of them were males. Indication included acute complications (4 acute chest syndrome, 2 priapism, 2 surgical prophylaxis) and chronic ones (1 pulmonary hypertension and 1 chronic liver disease). The total number of procedures performed were 45 and it varied per patient from 1 to 19 (median 1.5). In each procedure, we used on average 5.33 (± 0.98, standard deviation) RBCU and the inlet volume of the procedures was 3045 (± 881) mL on average. In acute RBCX procedures, the system predicted a postapheresis hematocrit of 29% (mean) (confidence interval (CI) 95%: 28 - 30) and HbS 35.9% (CI 95%: 31.2 - 40.6). The patient’s mean postapheresis hematocrit were 28.7% (CI 95%: 27.6 - 29.8) and HbS 33.3% (29.1 - 37.5); achieving an HbS reduction of 51% (CI 95%: 44.8 - 57.2). In chronic RBCX procedures, the system predicted a postapheresis hematocrit of 28.1% (mean) (CI 95%: 28 - 28.2) and HbS 20.6% (CI 95%: 20 - 24.1). The patient’s mean postapheresis hematocrit was 29.1% (CI 95%: 28.5 - 29.7) and HbS 19.5% (16.1 - 23), achieving an HbS reduction of 53.1% (CI 95%: 50.7 - 55.5). In figure 1 we represent the difference between predicted and measured hematocrit and HbS as a Bland - Altman Plot. A perfect correlation would equal to “0.00”, and a negative result indicates that we achieved a lower value than predicted. The purple lines represent the difference (real-predicted) mean and its standard deviation. Summary/Conclusion: The differences that we detected (not statistically significant) were lower than the predicted and as thus favorable for the patients (lower HbS and hematocrit) in acute procedures. In chronic procedures the postapheresis hematocrit presented statistically significant differences, but the CI is extremely narrow with mean differences in 1% not clinically relevant. In conclusion we have demonstrated that our RBCX procedure is accurate and achieves the expected results in real-life with no clinically significant deviations.Keywords: Apheresis, Sickle cell disease